The hour, titled “Henny Penny The Sky Is Falling,” “revolves around the murder of a man who was looking for better and more efficient ways to identify what are known as Earth-killer asteroids,” executive producer Rob Doherty previews. “So there’s mystery on top of mystery as to why anyone would want to kill someone who might be able to help NASA locate and, hopefully, divert a small planetoid hurdling towards Earth.”

During the course of the investigation, Sherlock must turn to Yeoman’s character, a scientist, for assistance with the case. “It’s a fun and very colorful role,” Doherty adds.